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diff --git a/progs/glsl/CH11-toyball.frag.txt b/progs/glsl/CH11-toyball.frag.txt
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+++ b/progs/glsl/CH11-toyball.frag.txt
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+//
+// Fragment shader for procedurally generated toy ball
+//
+// Author: Bill Licea-Kane
+//
+// Copyright (c) 2002-2003 ATI Research 
+//
+// See ATI-License.txt for license information
+//
+
+varying vec4 ECposition;   // surface position in eye coordinates
+varying vec4 ECballCenter; // ball center in eye coordinates
+
+uniform vec4  LightDir;     // light direction, should be normalized
+uniform vec4  HVector;      // reflection vector for infinite light source
+uniform vec4  SpecularColor;
+uniform vec4  Red, Yellow, Blue;
+
+uniform vec4  HalfSpace0;   // half-spaces used to define star pattern
+uniform vec4  HalfSpace1;
+uniform vec4  HalfSpace2;
+uniform vec4  HalfSpace3;
+uniform vec4  HalfSpace4;
+
+uniform float InOrOutInit;  // = -3
+uniform float StripeWidth;  // = 0.3
+uniform float FWidth;       // = 0.005
+
+void main()
+{
+    vec4  normal;              // Analytically computed normal
+    vec4  p;                   // Point in shader space
+    vec4  surfColor;           // Computed color of the surface
+    float intensity;           // Computed light intensity
+    vec4  distance;            // Computed distance values
+    float inorout;             // Counter for computing star pattern
+
+    p.xyz = normalize(ECposition.xyz - ECballCenter.xyz);    // Calculate p
+    p.w   = 1.0;
+
+    inorout = InOrOutInit;     // initialize inorout to -3
+
+    distance[0] = dot(p, HalfSpace0);
+    distance[1] = dot(p, HalfSpace1);
+    distance[2] = dot(p, HalfSpace2);
+    distance[3] = dot(p, HalfSpace3);
+
+#if 1
+    distance = smoothstep(-FWidth, FWidth, distance);
+    inorout += dot(distance, vec4(1.0));
+
+    distance.x = dot(p, HalfSpace4);
+    distance.y = StripeWidth - abs(p.z);
+    distance = smoothstep(-FWidth, FWidth, distance);
+    inorout += distance.x;
+
+    inorout = clamp(inorout, 0.0, 1.0);
+
+    surfColor = mix(Yellow, Red, inorout);
+    surfColor = mix(surfColor, Blue, distance.y);
+
+    // normal = point on surface for sphere at (0,0,0)
+    normal = p;
+
+    // Per fragment diffuse lighting
+    intensity  = 0.2; // ambient
+    intensity += 0.8 * clamp(dot(LightDir, normal), 0.0, 1.0);
+    surfColor *= intensity;
+
+    // Per fragment specular lighting
+    intensity  = clamp(dot(HVector, normal), 0.0, 1.0);
+    intensity  = pow(intensity, SpecularColor.a);
+    surfColor += SpecularColor * intensity;
+
+    gl_FragColor = surfColor;
+#else
+    gl_FragColor = distance;
+#endif
+}